Core–Shell versus Other Structures in Binary Cu38–nMn Nanoclusters (M = Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au; n = 1, 2, and 6): Theoretical Insight into Determining Factors

DFT calculations of binary transition-metal nanoclusters Cu38–nMn (M = Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au; n = 1, 2, and 6) clearly show that a core–shell structure Cu32M6(core) with M in the core is stable for M = Ru, Rh, Os, and Ir but unstable for M = Pd, Ag, Pt, and Au. These results are consistent with the segregation energies evaluated for Cu37M. Electron population is more accumulated on the core M atoms in Cu38–nMn(core) (M = Ru, Rh, Os, and Ir) than on the core Cu atoms in Cu38. Such electron accumulation substantially occurs for M = Ru, Rh, Os, and Ir because the d orbitals of these transition metals are not fully occupied. A linear relationship was first found between the segregation energy and the increase in the d-orbital population of the core atom, indicating that the electron accumulation at the Mn core is one of the important factors for the segregation energy and the stabilization of the core–shell structure; in other words, a core–shell structure with M atom(s) in the core is stable whe...